The present embodiments relate to a magnetic resonance tomography apparatus that is used for examining an object based on the principle of nuclear spin resonance.
Magnetic resonance tomography apparatuses (e.g., nuclear spin tomography apparatuses) include imaging devices by which the spins of atomic nuclei are aligned and excited in order thereby to generate images of the tissue under investigation. A static background magnetic field is generated in a magnetic resonance tomography apparatus for that purpose. Radio frequency signals are transmitted at the known Larmor frequency that is dependent, for example, on the material under investigation and the magnetic field strength of the static background field. After the radio frequency signals are switched off, a magnetic resonance signal is received via corresponding magnetic resonance receive antennas in the system, and images of the internal structure of the examined object are generated in a known manner based on the evaluation of the magnetic resonance signal.
Arrays including local coils may be employed as magnetic resonance receive antennas in conventional magnetic resonance tomography apparatuses in order to optimize the signal-to-noise ratio and the examination time. In this context, local coils are antennas that are attached close to the body or to the part of the body of the patient that is to be examined, and the magnetic resonance signals are acquired from inside the body. The recorded signals are forwarded to the evaluation system of the imaging device.
The use of local coils as magnetic resonance receive antennas has the disadvantage that the use includes a considerable amount of additional time for attaching the coils to the patient. Local coils are uncomfortable and constricting for the patient, making examinations more protracted or even impossible. The cabling of the local coils is complicated and laborious, is susceptible to wear and tear, and constitutes a risk for the patient if insulation measures are inadequate, or the sheath currents are not adequately suppressed.
In order to circumvent the above-described problems, it is known from the prior art to utilize magnetic resonance tomography apparatuses having a “remote body array” that includes a plurality of magnetic resonance receive antennas arranged at a distance from the body (e.g., no longer in direct contact with the body of the patient). A magnetic resonance tomography apparatus having an array of magnetic resonance receive antennas remote from the body is disclosed in the publication WO 2010/097375 A2.